Glass containers, including glass bottles, are formed in a process that is well-known in the art. The various components of the glass (i.e. the batch) are heated until they have melted. A gob of this melted glass is next formed into a parison in a so-called blanking or parison mold. The parison formed is moved from the blanking mold to a finishing or blow mold, where the finished bottle is shaped.
Mass production of glass bottles is generally carried out in a well-known IS (individual section) glass forming machine which has a plurality of glass forming means integrated into a single plural-section machine fed by a single source of molten glass. The sections are operated in synchronism in such relative phase relationship to permit the several sections to acquire gobs of molten glass in ordered sequence from the single source.
Thus, as one of the sections is receiving a gob from the feeding means, another section is delivering a finished article to an output conveyor and other sections are engaged in various forming steps between receipt of the gob and production of the finished article. The sequence of operation is controlled by a timing mechanism that may be either mechanically or electronically controlled. This timing mechanism sequentially initiates mechanical devices in a predetermined synchronized sequence through automatic control systems.
The IS machines have two molds in each individual mold section, whereby a gob is received in a first mold, called a parison mold, for the initial process of forming a parison, followed by transfer of the parison to a second mold, called the blow or finishing mold, for blowing the parison to its final configuration. A transfer arm is pivoted between the parison mold and the finishing mold, and the parison is formed in an inverted position in the parison mold and is transferred to the finishing mold in an upright position. This process is generally disclosed in U.S. Pat. No. 3,762,907, incorporated herein by reference.
U.S. Pat. No. 4,983,203 issued to Erb et al., also incorporated herein by reference, discloses a glass forming system wherein parison mold halves are mounted on a pair of mold hanger arms movable between a retracted position and a closed position at a parison-forming station. Pairs of neck ring mold halves forming neck ring molds are held together at the parison-forming station and are configured for nesting surrounding engagement by the parison mold halves when the parison mold halves are brought together.
The opening and closing of the molds are accomplished typically by operation of an air cylinder acting through a series of linkages, typically involving shafts, pins and levers. The mold hanger arms are each cantilever-mounted at one end for pivotal rotation about a post, and the linkages serve to move the arms in an arcuate motion between closed and open positions. The air cylinder and linkages also provide the clamping forces necessary to hold the mold halves closed during the pressing of the glass at the parison-forming station or the blowing of the glass at the finishing mold station. This system has many wear points, and as the wear increases, it causes misalignment of parts and causes the mold halves to fail to close tightly. Moreover, particularly in the case of systems having long hanger arms, such wear will cause the hanger arms to sag downward from a horizontal position, causing misalignment of the neck ring mold halves with respect to the parison mold halves. As a result, defective products are formed. Additionally, particularly in multi-mold assemblies, relatively massive hanger arms are necessary to maintain clamping forces to hold the molds in proper alignment. This increased mass in turn reduces the operating speed of the system.
Various older designs eliminate the sagging problem of the hanger arm outer ends by physically supporting the lower surfaces of the hanger arms by means of substrate plates against which the lower faces of the hanger arms are frictionally supported. Examples of such systems are shown in U.S. Pat. No. 1,213,853 issued to Ferngren on Jan. 30, 1917; U.S. Pat. No. 1,331,471 issued to Peiler, et. al., on Feb. 17, 1920 and U.S. Pat. No. 2,304,736 issued to Louden et al on Dec. 8, 1942. The mold halves shown therein are provided with terminal projections or jaws disposed in general prolongation of the major direction of the hanger. In the Ferngren and Peiler systems a wedge is provided to be driven between the jaws, the jaws and wedge mating surfaces causing the mold halves to be pressed together. A similar function is provided in the Louden patent by forcing camming surfaces to engage such projections when a pair of cams are forced towards the general vicinity of the mold halves. These patents appear to show adequate mold closure systems, but since they are all used in conjunction with table-supported hangers, the alignment problem does not arise.
On the other hand, U.S. Pat. No. 3,528,796, issued to Trahan on Sep. 15, 1970 shows a true cantilever dual mold hanger system and locking mechanism. As in the Ferngren and Peiler patents, a wedge is configured to engage forwardly extending projections on each mold hanger, the wedge being driven horizontally towards the hanger support pivot 18 (FIG. 1). This action, while securely closing the hanger arms and their associated mold halves, does not provide a solution to the removal of cantilever sag in such systems.